Version 0.4

• #2 TextFile: Add ``..`` to access the parent directory.
• TextFile: Add optional parameter Encoding.
  The possible values are UTF-8, UTF-16-le, UTF-16-be, UTF-32-le and UTF-32-be.
  When not provided, the encoding is guessed automatically, as before.
• #12 TextFile: Strip the byte order mark from text content.
• #14 Env and TextFile: Add optional parameter EnsureExists.
  When true, if the file or environment variable doesn't exist, a compile-time error is raised.
  Otherwise, DefaultValue is used, or an empty string if not provided, as before.